An Ethernet Virtual Interconnect (EVI) network includes a core network and a site network. The site network includes an edge network, i.e., a network between convergence devices and edge devices, and an access network, i.e. a network between access devices and convergence devices. The EVI extends Virtual Local Area Networks (VLANs) to different sites. Independent EVI service instances consist of these extended VLANs. Each EVI service instance is identified by a Network ID to number the EVI service instances globally and uniformly. Intra-VLAN forwarding of different EVI service instances on a device may be isolated from each other.